1. Field of the Invention
The present invention generally relates to a sealing method, and more particularly to an improved method for sealing optical windows in explosive initiators.
2. Prior Art
Certain explosive initiators employ optical windows to transfer light from a laser source into the device to initiate an explosion. Some initiators of this type have been made using finished windows that are sealed to the initiator walls with polymeric materials such as epoxy resin. Other optical windows have been made by casting glass into a hole in a metal plate and then grinding, polishing and coating it while in the metal plate, and finally welding the metal plate to the rest of the cartridge body to form the finished sealed optical window.
However, polymeric seals generally have higher leak rates than are acceptable for many explosive initiator applications and cannot stand extreme temperatures and pressures. Moreover, casting an optical window into a metal part and finishing the subassembly before welding it into a cartridge has the disadvantage of being a process with many steps, each of which adds to labor costs and the potential for loss from mistakes. It also limits design flexibility and reduces the number of parts that can be processed at once in a given piece of equipment in contrast to the larger number that can be done if the windows alone are processed.
Accordingly, there remains a need for an improved method of sealing optical windows into explosive initiators. Such method should be rapid, simple, inexpensive, reproducible and efficient. It should provide high quality optical window seals capable of withstanding extremes of temperature and pressure without leaking.